The present invention relates to a color charge-coupled device, and more particularly, to a color charge-coupled device and a method of manufacturing the same, which is suited to improve sensitivity and to prevent color mixing.
FIGS. 1A to 1D are cross-sectional views for illustrating a method of manufacturing a conventional color charge-coupled device.
Referring to FIG. 1A, through a general process, a plurality of photodiodes 11 for generating a signal charge according to an intensity of light incident and a plurality of vertical charge-coupled devices (VCCDS) 12, i.e., charge transmission regions for transmitting the signal charge generated from photodiodes 11, are alternatley formed on a substrate 10. A pad 13 is formed on one side of the substrate excluding a portion where the photodiodes and VCCDs are formed, thereby forming a black/white charge-coupled device.
Of photodiodes 11, reference numeral 11-1 represents a photodiode corresponding to a first color. Reference numeral 11-2 represents a photodiode corresponding to a second color. Reference numeral 11-3 represents a photodiode corresponding to a third color.
A first planarizing film 14 is formed on the entire surface of substrate 10 in which the charge-coupled device is formed.
Thereafter, a color filter layer 15 is formed on first planarizing film 14. Specifically, after forming a resin layer on first planarizing film 14, the resin layer is dyed and adhered with the first color. The colored resin layer is photo-etched, thereby forming a first color filter layer 15-1. By repeating the above process, second and third color filter layers 15-2 and 15-3 are formed on first planarizing film 14, respectively. As a result, the color filter layers of three colors are sequentially formed on first planarizing film 14, thereby completing a process of forming color filter layer 15.
After completing a process of forming color filter layer 15, a second planarizing film 16 is formed on first planarizing film 14 including color filter layer 15, thereby planarizing the substrate again.
Referring to FIG. 1B, as a material 17 for microlens, a photoresist film is coated on second planarizing film 16. By performing a photo-etching process, material 17 for microlens is patterned so as to be left only on each photodiode region 11.
Referring to FIG. 1C, patterned material 17 for microlens is thermally flowed, thereby forming convex microlenses 18 on second planarizing film 16 above each photodiode 11.
Referring to FIG. 1D, a photoresist film 19 is coated on second planarizing film 16 on which microlenses 18 are formed. Then, photoresist film 19 above pad 13 is removed through a photo-etching process, thereby exposing second planarizing film 16.
Exposed second planarizing film 16 and first planarizing film 14 placed thereunder are sequentially etched by using photoresist film 19 as a mask, thereby exposing pad 13.
Finally, after exposing pad 13, remaining photoresist film 19 is removed, thereby producing the conventional color charge coupled device.
In case that the color charge coupled device manufactured according to the above-discussed method is applied to a camera, light incident through a camera lens is converged by microlens 18, and the light converged by microlens 18 is selectively permeated through color filter layer 15. That is, among color filter layers 15, first color filter layer 15-1 selectively permeates light only for the first color, of light converged by the microlens, and applies it to photodiode 11-1 corresponding to the first, color among plurality of photodiodes 11. Second color filter layer 15-2 selectively permeates light only for the second color and applies it to photodiode 11-2 corresponding to the second color. Third color filter layer 15-3 selectively permeates light only for the third color and applies it to photodiode 11-3 corresponding to the third color.
Accordingly, light incident upon each photodiode 11 is transformed photoelectrically, thereby generating a signal charge. The charge generated from photodiode 11 is transmitted to VCCD 12 by the signal transmission operation of a general charge-coupled device, and then, transmitted to a horizontal charge-coupled device (HCCD) (not shown). After sensing the signal charge transmitted to the HCCD due to a floating diffusion from the tip of device, the signal charge is amplified through an amplifier (not shown) and then, transmitted to a peripheral circuit.
However, the method of manufacturing the conventional color coupled device involves the following problems.
First, in order to form the color filter layer according to the conventional method, a photo-etching process is performed three times. During the photo-etching process of forming the color filter layer, a photoresist film is left on an undesired portion, thereby causing color mixing. Further, light is permeated between neighboring color filter layers. This also causes color mixing.
Secondly, since the second planarizing film exists between the microlens and color filter layer, light is likely to be scattered. Further, due to the distance offset between the microlens and color filter layer, it is difficult to adjust a depth of focus to the photodiode.
Thirdly, the second planarizing film is formed after forming the color filter layer, complicating the whole process. This also consumes a great amount of a manufacturing time. The thickness of the device is increased as well.